Studies
Explore research connecting ingredients and health goals.
23 ingredient–goal connections
Mental FocusandCaffeine
128published studies
The available controlled research supports caffeine's ability to improve alertness and performance on tasks requiring sustained attention and quick responses. Benefits occur in some people who do not regularly consume caffeine, so withdrawal relief does not explain every positive finding. Caffeine can also reduce some attention lapses during sleep loss.
However, faster responses do not necessarily mean better reasoning, memory or control over mistakes. Results vary across tasks, with some studies finding no improvement and others showing poorer accuracy, memory or inhibition despite greater alertness. Research during sleep deprivation similarly suggests that caffeine may improve vigilance without fully restoring more complex performance.
Habitual consumption complicates the picture: part of the apparent benefit can reflect reversal of withdrawal, and sustained use has not consistently produced a net improvement in cognition. Anxiety, jitteriness and increased blood pressure also appear in the supplied trials. The clearest conclusion is a temporary benefit for wakefulness and attention, with less reliable effects on broader mental performance.
128 linked studies · 25 sampled for detail · Sep 27, 2026
Study types
- Randomized trial73
- Clinical trial24
- Narrative review11
- Meta-analysis6
- Systematic review5
- Non-randomized trial4
- Cross-sectional study2
- Observational study2
- Scoping review1
Published by year
- 41Earlier
- 62010
- 32011
- 22012
- 82013
- 22014
- 62015
- 12016
- 42017
- 62018
- 62019
- 72020
- 82021
- 62022
- 52023
- 62024
- 42025
- 72026
Findings over time
Numbers above bars show study counts. Earlier groups years before 2010.
20267 studies
- Supportive4(57.1%)
- Mixed2(28.6%)
- No effect1(14.3%)
- Adverse0(0%)
- Unclassified0(0%)
Population over time
Reported participants by publication year. Select a year to see the total and reporting coverage.
— Participant count not reported. Earlier groups years before 2010.
2026264 reported participants
Counts reported by 4 of 7 studies. 3 without a reported count.
Totals sum reported counts across studies and reviews; participants may overlap between sources.
Showing 5 top-ranked studies for Caffeine and Mental Focus.
Top studies
Caffeine · Mental FocusHighest ranked first- Effects of modafinil and caffeine on night-time vigilance of air force crewmembers: A randomized controlled trial.SupportiveView source for Effects of modafinil and caffeine on night-time vigilance of air force crewmembers: A randomized controlled trial. (opens in a new tab)
Journal of psychopharmacology (Oxford, England)
Finding Caffeine and modafinil differed significantly from placebo on all measured endpoints except VigTrack mean tracking error.
- Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers.SupportiveView source for Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers. (opens in a new tab)
Journal of psychopharmacology (Oxford, England)
Finding Short-term withdrawal did not affect performance measures, despite increased self-reported withdrawal symptoms.
- Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation.SupportiveView source for Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation. (opens in a new tab)
Journal of sleep research
Finding Caffeine, dextroamphetamine, and modafinil each improved psychomotor-vigilance speed and objective alertness versus placebo.
- Effects of caffeine on mood and performance: a study of realistic consumption.SupportiveView source for Effects of caffeine on mood and performance: a study of realistic consumption. (opens in a new tab)
Psychopharmacology
Finding Both caffeine regimens increased alertness and anxiety and improved performance across several reaction, vigilance, sustained-response, and dual-task measures.
- Effects of caffeine or diphenhydramine on visual vigilance.SupportiveView source for Effects of caffeine or diphenhydramine on visual vigilance. (opens in a new tab)
Psychopharmacology
Finding Compared with placebo, 200 mg caffeine increased correct responses and decreased response times on the visual vigilance task.
Counts reflect published studies in our database, not the strength of a benefit. A study may appear in more than one connection.